The present invention relates to the management of events in a standard computer system comprising a central unit connected to memory units and peripheral devices by a data bus providing for a multimaster configuration.
Controlling certain processes necessitates detecting parameters and sending appropriate command instructions in real time or on an extremely short timescale of the order of one microsecond (μs). This type of application is encountered in the aerospace field and in the control of certain industrial processes.
There exist real-time control systems based on programmable logic controllers. The drawbacks of those logic controllers are their limited processing power and, more importantly, their incompatibility with standard computer networks, because the specific nature of systems based on logic controllers rules out connecting them to a standard computer network.
Moreover, real-time control of the various units of a computer system is not possible in the case of a standard computer system, for example one based on a microcomputer, provided with high-speed data buses or communications channels (for example a PCI bus) and controlled by a multitasking operating system (for example Windows NT).
FIG. 13 is a very diagrammatic representation of a standard computer system comprising a central unit 10 controlled by a 10 MHz clock (not shown), for example, a memory unit 20 and peripheral devices 30, 40 and a software environment (operating system) necessary for processing information. The central unit 10 provides the control function and carries out arithmetic and logic operations. The memory unit 20 comprises random-access memory 21 and read-only memory 23, and the peripheral devices comprise input and output interfaces. Data, addresses, and control and synchronization signals are exchanged between the various units of the computer system via a data bus 50.
In the above kind of standard computer system, provided with a “real-time” operating system, there is no provision for fast and accurate processing of incoming discrete signals or data on the data bus 50. That kind of operating system provides only for dialogue between the central unit and one other unit, with response times of the order of one millisecond (ms), which are unsuited to processes comprising important and highly sensitive parameters, as encountered in the aerospace field.